EBOLA and The Importance of
Situational Awareness

As of Sep. 30,
the Ebola virus
had killed more
than 3,000
people in the
West African
countries of
Liberia, Sierra
Leone, Guinea
and Nigeria,
according to the
latest numbers
released by
the World Health
Organization.

As the virus
spreads and
medical workers
feverishly
battle to
contain it, we
wanted to know,
how exactly is
this virus
transmitted from
human to human?

What is Ebola?

Ebola is one of the world’s most virulent diseases. It comes from an extended family of viruses called Filoviridae, which also include the deadly Marburg virus. It is a swift and effective killer, known to kill up to 90 percent of those it infects. And it is a “hemorrhagic fever virus,” which means it causes fluid to leak from blood vessels, resulting in a dangerously low drop in blood pressure.

Understanding Ebola requires an understanding of viruses and how they work. “Viruses,” science writer Carl Zimmer writes in his book “A Planet of Viruses”, “can replicate themselves, despite their paltry genetic instructions, by hijacking other forms of life. They… inject their genes and proteins into a host cell, which they [manipulate] into producing new copies of the virus. One virus might go into a cell, and within a day, a thousand viruses [come] out.”

All viruses contain “attachment proteins,” which, as the name suggests, attach to host cells through the cells’ “receptor sites.” This is how they invade healthy human cells.

While some virus particles are shaped like spheres, the particles that make up Ebola are filament-like in structure, giving them more surface area to potentially attack a greater number of cells. Each Ebola virus particle is covered in a membrane of these attachment proteins, or glycoproteins.

“[The virus] has a tremendous number of glycoproteins, which can increase its ability to affect cells,” said Richard Cummings, chair of Emory’s Dept. of Biochemistry and director of the National Center for Functional Glycomics. “It’s extremely infectious in that regard.”

Imagine Ebola’s glycoproteins as giant oak trees with branches and leaves, said Erica Ollmann Saphire, a structural biologist at the Scripps Research Institute. The Ebola virus has its own critical receptor site, which lies beneath these branches and leaves to avoid detection from the immune system. Each glycoprotein can attach itself to a host cell in a number of different ways, but once its branches fasten themselves to a host cell’s molecules, that host cell pulls in the attachment protein, slicing off its leaves and branches and exposing the trunk, the virus’s receptor site.

Ebola spreads
through direct
contact with
infected bodily
fluids or
tissue. The
virus can be
transmitted when
an infected
person’s vomit,
blood or other
fluids contact
another person’s
mouth, eyes or
openings in
their skin, said
Dr. Ameesh
Mehta, an
infectious
disease doctor
at Emory
University.

Even after a
person has died,
the virus
persists. In
West Africa
where funeral
rites include
washing,
touching and
kissing corpses
by family
members, putting
the dead to rest
can be just as
deadly as caring
for a living
patient.

“Contact with
any aspect of it
is considered
very dangerous,”
Cummings said.
“Any physical
contact.”

Ebola’s
sucker punch is
its speed of
replication. At
the time of
death, a patient
can have 1
billion copies
of the virus in
one cubic
centimeter of
blood. In
comparison, HIV,
a similar virus,
has the same
rate at the time
of death. But
unlike HIV,
which only
infects two
types of immune
cells, Ebola
first infects
white blood
cells that
disable the
body’s ability
to destroy
foreign
substances,
then seizes
nearly every
cell type.

“It’s a systemic
viral infection
throughout your
body as opposed
to an infection
of just your
immune system,”
Saphire said.
“Patients may
die before
they’re able to
mount much of an
immune
response.”

This process
takes anywhere
from two to 21
days (though
it’s typically
between four to
10 days). When
the immune
system begins
breaking down,
the symptoms
begin to show.

Patients
experience
fevers,
headaches and
fatigue early
on. After the
virus overwhelms
healthy cells,
they burst,
causing a
chemical release
leading to
inflammation.
Their remains
are taken over
by other cells,
perpetuating the
virus. As the
symptoms worsen,
patients suffer
from bloody
diarrhea, severe
sore throat,
jaundice,
vomiting or loss
of appetite.

Infected cells
that haven’t yet
burst carry the
virus through
the bloodstream
to invade
different parts
of the body like
the lymph nodes,
spleen and
liver. When
infected cells
attach
themselves to
the inside of
blood vessels,
it weakens them,
causing fluids
to leak. This
triggers the
uncontrollable
bleeding for
which Ebola is
known, though it
only happens for
about 50 percent
of patients and
occurs mostly
inside the body.

In fatal cases,
blood pressure
plummets after
blood vessel
damage, and
death from shock
or multiple
organ failure
occurs within
six to 16 days.

The path ahead

Saphire is part
of a large,
multi-site team
made up of 25
laboratories
that’s mapping
Ebola’s
glycoprotein to
better
understand and
defeat the
virus. Among the
potential
strategies
they’re studying
is an antibody
cocktail called
ZMapp, an
experimental
drug that drew
media attention
after its use on
two U.S. aid
workers and
three Liberian
doctors. First
developed by the
U.S. Army
Medical Research
Institute for
Infectious
Diseases a
decade ago, this
“Ebola serum”
potentially
works to
neutralize the
virus by
preventing its
rearrangement
and flagging it
for destruction
by the immune
system.

Clinical trials
for ZMapp are
set to begin in
2015, but
according to
Saphire, doses
for
“experimental
compassionate
therapy,”
treatment
provided to
critically-ill
patients before
the drug has
been approved,
could be ready
in three months.

“The central
dogma of
molecular
biology is that
sequence
dictates fold,
which dictates
function,”
Saphire said.
“But Ebola does
more with less.
While the human
genome has
20,000 kinds of
genes, Ebola has
seven, and by
rearranging its
protein
structure, it
can carry out
far more than
seven
functions.”

How the EBOLA Virus
Attacks

EBOLA Virus Typical
Path through a Human

Ebola, Saphire
explained,
remodels its
molecules “like
a Transformer:
those toys that
unfold and
refold to change
between a robot
and a truck,”
she said. “We
don’t typically
expect molecules
in biology to do
that. We expect
proteins to have
one particular
form – just the
robot. If you
didn’t know that
the Ebola robot
would also
refold into a
truck, you would
design all your
drugs against
the robot
structure.”

In addition, due
to its extreme
nature, there
are far fewer
human studies on
Ebola than other
similar viruses.

“Ebola patients
are often too
sick to consent
to research,”
Mehta said.
These cases are
occurring in
poor
environments
where it’s hard
to collect the
samples to
really
understand the
pathogens. But
hopefully
science catches
up with the
clinical
phenomenon.”

While the recent
outbreak is not
expected to
reach far beyond
West Africa,
researchers like
science writer
Richard Preston
fear the
beginning of a
more deadly and
longer-lasting
epidemic if the
virus finds its
way to
metropolitan
areas like
Lagos, Nigeria,
which has a
population
larger than the
state of New
York.

Despite Ebola’s
pervasive
spread, Cummings
says the biggest
misconceptions
are that Ebola
is easily
transmitted and
that the
outbreak in West
Africa could
reach global
levels.

While one should
still exercise
caution,
Cummings says
the requirement
of transmission
of fluids makes
the disease more
difficult to get
if you’re not
directly
treating
patients.

“It is more
controllable
than people
realize.” But
prevention is
the key. By
learning how the
disease is
transmitted,
Preppers can
become aware of
this and avoid
situations where
infection is
likely.